In the manufacture of camshafts for internal combustion engines the cams and journals along the camshaft are machined and polished in different stages and it is necessary to efficiently move the parts from one operating station to another without any damage to the machined surfaces. Thus it is desired to transfer the part without touching the machined surfaces by another part or by the transfer mechanism.
In prior practice, one method of conveying camshafts involved transferring the parts stepwise from one holder to another thus advancing each part incrementally through many holders to the end of the conveyor. In the event an upstream holder was empty, the empty space was transferred down the conveyor thus making inefficient use of the apparatus. This type of conveyor is a non-accumulating conveyor; however, an accumulating type which fills in the empty spaces is preferred.
U.S. Pat. No. 4,561,536 to Weaver et al discloses an accumulating conveyor for spindle shaped parts having a series of overlapping rotors each carrying a pair of notched discs for holding a part and, upon rotation, transferring the part to the notch of the next disc. The rotors are chain driven through individual slip clutches which allow each rotor holding a part to stop with the part engaging the periphery of the next downstream rotor and wait until a notch on the downstream rotor removes the part from the stationary upstream rotor. From the standpoints of initial cost, maintenance, and machine integrity the clutches are not considered to be acceptable, particularly in the case of a long conveyor which would require perhaps hundreds of rotors and slip clutches. Weaver et al teaches the loading of parts at one end of the conveyor and the discharge at the other end. It is desirable, however, to top load the conveyor at a number of points along its length.